The major goal of the Cancer Epidemiology Program (CEP) is to understand the pathogenesis of human cancers at the molecular level through the use of observational and interventional studies in human populations. This effort includes a number of large prospective cohort investigations, case-control studies, population-based cross-sectional studies, and hospital-based projects, to identify etiologic risk factors and cancer biomarkers related to the multiple stages of tumorigenesis. Study populations derive from the Bronx/NYC AECC catchment area and regional/national and international inter-institutional collaborations. The scope of research has increased with faculty recruitment and expanded studies by senior CEP investigators. Substantial progress has been made in several molecular epidemiologic research areas. This includes (i) viral causes of cancer- human papillomavirus, simian virus 40, and hepatitis C virus;(ii) the epidemiology of breast cancer and its precursors;(iii) the role of host immunity including studies on immune compromised patients, immune genes (HLA and KIR), and specific immune responses to viral oncoproteins. New research initiatives include (iv) inflammation and cytokines in the development of colorectal cancer and polyps;(v) risk factors for head/neck cancer;(vi) endocrine-based cancer risk factors such as hyperinsulinemia and insulin-like growth factors (IGF), energy consumption, diabetes and obesity, sex hormones, and (vii) genetic epidemiology - studies of gene polymorphisms (e.g., in the insulin and IGF signaling pathways), variations in gene expression (involving use of mRNA arrays), and epigenetic changes (e.g., DMA methylation). Studies on HPV are being translated into therapeutic (vaccine) and screening approaches for cervical cancer. A Biostatistics Shared Resource was established with several members based in the CEP, with ongoing methodological research. There has been increased research in cancerrelated behaviors - substance abuse (e.g., cigarettes/alcohol), energy consumption/obesity, and exercise, with funded intervention efforts. There are currently 16 program members from 7 academic departments supported by 12 NCI ($2.6M Direct) and 4 other NIH grants. There are five new members. Since the last CCSG review there have been 218 research papers by program members of which 19% represent intraprogrammatic, and 7% interprogrammatic collaborative publications.